sat_runner.cc

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// Copyright 2010-2024 Google LLC
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#include <cstdlib>
#include <string>
 
#include "absl/flags/flag.h"
#include "absl/flags/parse.h"
#include "absl/flags/usage.h"
#include "absl/log/check.h"
#include "absl/log/flags.h"
#include "absl/log/initialize.h"
#include "absl/strings/match.h"
#include "absl/strings/str_format.h"
#include "absl/strings/string_view.h"
#include "google/protobuf/arena.h"
#include "google/protobuf/text_format.h"
#include "ortools/base/helpers.h"
#include "ortools/base/logging.h"
#include "ortools/base/options.h"
#include "ortools/base/path.h"
#include "ortools/sat/boolean_problem.h"
#include "ortools/sat/boolean_problem.pb.h"
#include "ortools/sat/cp_model.pb.h"
#include "ortools/sat/cp_model_solver.h"
#include "ortools/sat/cp_model_utils.h"
#include "ortools/sat/model.h"
#include "ortools/sat/opb_reader.h"
#include "ortools/sat/sat_cnf_reader.h"
#include "ortools/sat/sat_parameters.pb.h"
#include "ortools/util/file_util.h"
#include "ortools/util/sorted_interval_list.h"
 
ABSL_FLAG(
    std::string, input, "",
    "Required: input file of the problem to solve. Many format are supported:"
    ".cnf (sat, max-sat, weighted max-sat), .opb (pseudo-boolean sat/optim) "
    "and by default the CpModelProto proto (binary or text).");
 
ABSL_FLAG(
    std::string, hint_file, "",
    "Protobuf file containing a CpModelResponse. The solution will be used as a"
    " hint to bootstrap the search.");
 
ABSL_FLAG(std::string, domain_file, "",
          "Protobuf file containing a CpModelResponse. If present, the "
          "tightened models will be used to reduce the domain of variables.");
 
ABSL_FLAG(std::string, output, "",
          "If non-empty, write the response there. By default it uses the "
          "binary format except if the file extension is '.txt'.");
 
ABSL_FLAG(std::string, params, "",
          "Parameters for the sat solver in a text format of the "
          "SatParameters proto, example: --params=use_conflicts:true.");
 
ABSL_FLAG(bool, wcnf_use_strong_slack, true,
          "If true, when we add a slack variable to reify a soft clause, we "
          "enforce the fact that when it is true, the clause must be false.");
ABSL_FLAG(bool, fingerprint_intermediate_solutions, false,
          "Attach the fingerprint of intermediate solutions to the output.");
 
namespace operations_research {
namespace sat {
namespace {
 
void TryToRemoveSuffix(absl::string_view suffix, std::string* str) {
  if (file::Extension(*str) == suffix) *str = file::Stem(*str);
}
 
std::string ExtractName(absl::string_view full_filename) {
  std::string filename = std::string(file::Basename(full_filename));
  // The order is important as '.pb.txt.gz' is a common suffix.
  TryToRemoveSuffix("gz", &filename);
  TryToRemoveSuffix("txt", &filename);
  TryToRemoveSuffix("pb", &filename);
  TryToRemoveSuffix("pbtxt", &filename);
  TryToRemoveSuffix("proto", &filename);
  TryToRemoveSuffix("prototxt", &filename);
  TryToRemoveSuffix("textproto", &filename);
  TryToRemoveSuffix("bin", &filename);
  return filename;
}
 
bool LoadProblem(const std::string& filename, absl::string_view hint_file,
                 absl::string_view domain_file, CpModelProto* cp_model) {
  if (absl::EndsWith(filename, ".opb") ||
      absl::EndsWith(filename, ".opb.bz2")) {
    OpbReader reader;
    LinearBooleanProblem problem;
    if (!reader.Load(filename, &problem)) {
      LOG(FATAL) << "Cannot load file '" << filename << "'.";
    }
    *cp_model = BooleanProblemToCpModelproto(problem);
  } else if (absl::EndsWith(filename, ".cnf") ||
             absl::EndsWith(filename, ".cnf.xz") ||
             absl::EndsWith(filename, ".cnf.gz") ||
             absl::EndsWith(filename, ".wcnf") ||
             absl::EndsWith(filename, ".wcnf.xz") ||
             absl::EndsWith(filename, ".wcnf.gz")) {
    SatCnfReader reader(absl::GetFlag(FLAGS_wcnf_use_strong_slack));
    if (!reader.Load(filename, cp_model)) {
      LOG(FATAL) << "Cannot load file '" << filename << "'.";
    }
  } else {
    CHECK_OK(ReadFileToProto(filename, cp_model));
  }
 
  // Read the hint file.
  if (!hint_file.empty()) {
    CpSolverResponse response;
    CHECK_OK(ReadFileToProto(hint_file, &response));
    if (!response.solution().empty()) {
      CHECK_EQ(response.solution_size(), cp_model->variables_size())
          << "The hint from the response proto is not compatible with the "
             "model proto";
 
      cp_model->clear_solution_hint();
      for (int i = 0; i < cp_model->variables_size(); ++i) {
        cp_model->mutable_solution_hint()->add_vars(i);
        cp_model->mutable_solution_hint()->add_values(response.solution(i));
      }
    } else {
      LOG(INFO) << "The response proto has no solutions, ignoring.";
    }
  }
 
  // Read the tightened domain file.
  if (!domain_file.empty()) {
    CpSolverResponse response;
    CHECK_OK(ReadFileToProto(domain_file, &response));
    if (!response.tightened_variables().empty()) {
      CHECK_EQ(response.tightened_variables_size(), cp_model->variables_size())
          << "The tighened variables from the response proto is not "
             "compatible with the model proto";
 
      for (int i = 0; i < cp_model->variables_size(); ++i) {
        IntegerVariableProto* var_proto = cp_model->mutable_variables(i);
        const Domain tightened_domain =
            ReadDomainFromProto(response.tightened_variables(i));
        const Domain new_domain =
            ReadDomainFromProto(*var_proto).IntersectionWith(tightened_domain);
        FillDomainInProto(new_domain, var_proto);
      }
    } else {
      LOG(INFO) << "The response proto has no tightened variable domains, "
                   "ignoring.";
    }
  }
 
  // Set the name if not present.
  if (cp_model->name().empty()) {
    cp_model->set_name(ExtractName(filename));
  }
 
  return true;
}
 
int Run() {
  SatParameters parameters;
  if (absl::GetFlag(FLAGS_input).empty()) {
    LOG(FATAL) << "Please supply a data file with --input=";
  }
 
  // Parse the --params flag.
  parameters.set_log_search_progress(true);
  if (!absl::GetFlag(FLAGS_params).empty()) {
    CHECK(google::protobuf::TextFormat::MergeFromString(
        absl::GetFlag(FLAGS_params), &parameters))
        << absl::GetFlag(FLAGS_params);
  }
 
  // Read the problem.
  google::protobuf::Arena arena;
  CpModelProto* cp_model =
      google::protobuf::Arena::Create<CpModelProto>(&arena);
  if (!LoadProblem(absl::GetFlag(FLAGS_input), absl::GetFlag(FLAGS_hint_file),
                   absl::GetFlag(FLAGS_domain_file), cp_model)) {
    CpSolverResponse response;
    response.set_status(CpSolverStatus::MODEL_INVALID);
    return EXIT_SUCCESS;
  }
 
  Model model;
  model.Add(NewSatParameters(parameters));
  if (absl::GetFlag(FLAGS_fingerprint_intermediate_solutions)) {
    // Let's add a solution callback that will display the fingerprint of all
    // solutions.
    model.Add(NewFeasibleSolutionLogCallback([](const CpSolverResponse& r) {
      return absl::StrFormat(
          "fingerprint: %#x",
          FingerprintRepeatedField(r.solution(), kDefaultFingerprintSeed));
    }));
  }
  const CpSolverResponse response = SolveCpModel(*cp_model, &model);
 
  if (!absl::GetFlag(FLAGS_output).empty()) {
    if (absl::EndsWith(absl::GetFlag(FLAGS_output), "txt")) {
      CHECK_OK(file::SetTextProto(absl::GetFlag(FLAGS_output), response,
                                  file::Defaults()));
    } else {
      CHECK_OK(file::SetBinaryProto(absl::GetFlag(FLAGS_output), response,
                                    file::Defaults()));
    }
  }
 
  // The SAT competition requires a particular exit code and since we don't
  // really use it for any other purpose, we comply.
  if (response.status() == CpSolverStatus::OPTIMAL) return 10;
  if (response.status() == CpSolverStatus::FEASIBLE) return 10;
  if (response.status() == CpSolverStatus::INFEASIBLE) return 20;
  return EXIT_SUCCESS;
}
 
}  // namespace
}  // namespace sat
}  // namespace operations_research
 
static const char kUsage[] =
    "Usage: see flags.\n"
    "This program solves a given problem with the CP-SAT solver.";
 
int main(int argc, char** argv) {
  absl::InitializeLog();
  absl::SetProgramUsageMessage(kUsage);
  absl::ParseCommandLine(argc, argv);
  return operations_research::sat::Run();
}